Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 260504
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
1204 AM EST FRI DEC 26 2014

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 248 PM EST THU DEC 25 2014

A FAIRLY QUIET WEATHER PATTERN OVER THE UPPER GREAT LAKES REGION
FOR THE SHORT TERM FORECAST...WITH JUST SOME LIGHT SNOW POSSIBLE
OVER WESTERN/CENTRAL UPPER MICHIGAN TONIGHT INTO FRIDAY. A SURFACE
RIDGE HAS BEEN SHIFTING ACROSS UPPER MICHIGAN TODAY...BUT WITH
ABUNDANT MOISTURE BELOW THE SUBSIDENCE INVERSION AROUND 850MB ON
THE 12Z KGRB SOUNDING...MUCH OF THE CWA HAS SEEN LOW CLOUDS TODAY.
THERE IS AN EXCEPTION TO THE LOW CLOUDS...GENERALLY OVER CENTRAL
UPPER MICHIGAN WHERE THESE LOW CLOUDS HAVE SCATTERED OUT AND LEAVE
MID CLOUDS. THAT SCATTERING OUT WAS AIDED BY THE INCREASING
SOUTHWESTERLY FLOW AHEAD OF THE ELONGATED SURFACE TROUGH STRETCHING
FROM NORTHERN ONTARIO THROUGH MINNESOTA AND TO A LOW IN EASTERN
COLORADO. THIS TROUGH...ALONG WITH PIECES OF SHORTWAVE ENERGY SEEN
ON WATER VAPOR IMAGERY THIS AFTERNOON LIFTING NORTHEAST OUT OF
COLORADO...WILL BE THE PRIMARY FOCUS FOR THE FORECAST.

INITIAL VERY WEAK SHORTWAVE OVER MINNESOTA AND WEST CENTRAL
WISCONSIN WILL SHIFT NORTHEAST ACROSS CENTRAL/EASTERN UPPER
MICHIGAN THIS EVENING. THERE HAS BEEN PRECIPITATION ASSOCIATED WITH
THIS WAVE IN EASTERN SOUTH DAKOTA AND MINNESOTA EARLIER TODAY (TIED
IN WITH THE 800-600MB FGEN IN THAT AREA) AND IT HAS BEEN SPREADING
INTO WEST CENTRAL WISCONSIN OVER THE LAST COUPLE HOURS. BASED OF
THE ORIENTATION OF THE MID LEVEL WINDS AND FORECASTED TRACK OF THE
FGEN...WOULD EXPECT THE PRECIPITATION TO SHIFT EAST-NORTHEAST
ACROSS THE WISCONSIN BORDER EARLY THIS EVENING AND THEN MOVE ACROSS
PORTIONS OF CENTRAL/EASTERN UPPER MICHIGAN. THE SNOW WILL BE
FIGHTING A DRY LAYER BETWEEN 900-800MB THIS EVENING...WHICH WILL
KEEP SNOW ACCUMULATIONS LIGHT AND GENERALLY JUST A DUSTING. BUT
DEPENDING ON WHERE THE HEAVIEST BAND TRACKS...THERE COULD BE A FEW
LOCATIONS THAT SEE AMOUNTS UP TO A HALF INCH.

THEN THE SECOND SHORTWAVE WILL LIFT NORTHEAST OVER THE SURFACE
TROUGH AND THROUGH WESTERN LAKE SUPERIOR AND WESTERN UPPER MICHIGAN
LATER TONIGHT AND FRIDAY. LIKE THE INITIAL WAVE OF
PRECIPITATION...MID LEVEL (800-600MB) FGEN WILL REDEVELOP OVER THE
WESTERN CWA AND SHIFT THE FOCUS OF THE SNOW TO THE NORTHWEST THROUGH
THE NIGHT...AS THE MID LEVEL WINDS BACK AND REMAIN OVER THE WESTERN
CWA DURING THE MORNING HOURS ON FRIDAY BEFORE DIMINISHING AS THE
SHORTWAVE (AND ASSOCIATED DEEPER MOISTURE) DEPARTS. HIGHER
RESOLUTION MODELS FAIRLY CONSISTENT IN A STRIPE OF 0.05-0.10IN OF
QPF OVER THE WESTERN THIRD OF UPPER MICHIGAN LATE TONIGHT THROUGH
FRIDAY MORNING. WITH MUCH OF THE FORCING WITHIN AND AROUND THE
DGZ...COULD SEE SNOW RATIOS A LITTLE HIGHER IN THE BETTER FGEN
AREAS (TOWARDS 13-15 TO 1). THIS LEADS TO SNOWFALL AMOUNTS FROM A
HALF INCH TO A LITTLE OVER AN INCH IN THOSE AREAS. THERE COULD BE A
LITTLE ADDED SNOWFALL FROM LAKE ENHANCEMENT BEHIND THE SURFACE
TROUGH. INITIALLY...THERE WILL BE A POCKET OF DRIER AIR AT AND ABOVE
850MB OVER WESTERN LAKE SUPERIOR...ALONG WITH GENERALLY LIGHT
WEST-NORTHWEST FLOW AT THAT LEVEL...WHICH WILL LIMIT THE POTENTIAL
FOR LAKE ENHANCEMENT TONIGHT. BUT AS THE DEEPER MOISTURE PIVOTS
NORTHWEST TOWARDS THAT AREA LATE TONIGHT AND CONTINUES INTO FRIDAY
MORNING...THERE COULD BE SOME LIGHT ENHANCEMENT FOR AREAS FAVORED BY
NORTHERLY WINDS (BOUNDARY LAYER WIND DIRECTION) AFTER THE SURFACE
TROUGH MOVES THROUGH. WITH THE INVERSION STAYING AROUND
3-4KFT...THERE SHOULDN/T BE MUCH ADDITIONAL HELP BUT IT MAY GIVE
ANOTHER COUPLE TENTHS OF AN INCH OF SNOW.

THE SHORTWAVE WILL LIFT OUT OF THE AREA DURING THE AFTERNOON AND
PULL MUCH OF THE DEEPER MOISTURE OUT OF THE AREA. THIS LEADS TO
SOME CONCERNS OF ICE CRYSTAL PRESENCE OVER THE CENTRAL/EASTERN CWA.
ALTHOUGH THE POTENTIAL FOR PRECIPITATION IS LOW...WILL ADD A
MENTION OF DRIZZLE WITH THE SLIGHT CHANCE POPS FOR THAT AREA.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 447 PM EST THU DEC 25 2014

AFTER AN EXTENDED PERIOD OF MOSTLY ABOVE NORMAL TEMPS OVER THE LAST
2 WEEKS OR SO...A PATTERN CHANGE BACK TO A STRONG NE PACIFIC/WRN
NAMERICA RIDGE AND CNTRL/ERN NAMERICA TROF CONFIGURATION WILL OCCUR
DURING THE LONG TERM. THIS WILL BRING A RETURN OF A BLO NORMAL TEMP
REGIME TO THE UPPER LAKES...BEGINNING EARLY NEXT WEEK AND LASTING
THRU THE WEEK. AS FOR PCPN...THERE IS ONE SYSTEM EJECTING FROM THE
TROF CURRENTLY OVER THE ROCKIES THAT WARRANTS SOME WATCHING FOR FRI
NIGHT/SAT. OTHERWISE...WITH INCREASINGLY COLDER AIR AND NW FLOW
BECOMING DOMINANT...PCPN POTENTIAL WILL SHIFT MOSTLY TO THE LAKE
EFFECT SNOW BELTS NEAR LAKE SUPERIOR NEXT WEEK.

BEGINNING FRI NIGHT/SAT...A SHORTWAVE EJECTING FROM THE TROF
CURENTLY OVER THE ROCKIES IS FCST TO STREAK NE INTO THE GREAT LAKES.
AS THE SHORTWAVE LIFTS NE...IT WILL ENCOUNTER CONFLUENT FLOW BTWN
THE SRN BRANCH SUPPORTING THE ROCKIES TROF AND NRN BRANCH FLOW
ACROSS SRN CANADA. THIS WILL EVENTUALLY RESULT IN SHEARING/WEAKENING
OF THE SHORTWAVE. ON THE OTHER HAND...ENERGY IN THE WRN TROF LOOKS
QUITE VIGOROUS RIGHT NOW...AND OVERALL TREND FROM THE GEM/ECMWF/GFS
IS FOR THE SHORTWAVE TO WEAKEN LESS QUICKLY AS IT STREAKS NE.
DPROG/DT MODEL QPFS COMPARING 12Z DEC 24 AND 00Z DEC 25 ECMWF AND
00Z AND 12Z DEC 25 GEM ARE QUITE STRIKING IN THE INCREASE IN
QPF...AND THERE IS ALSO A SLIGHT NW TREND NOTED AS WELL. THE GFS/NAM
SHOW A SIMILAR TREND...THOUGH NOT AS DRAMATIC AS THE ECMWF/GEM.
GIVEN SIMILAR MULTI-MODEL TRENDS...WILL BEGIN EDGING POPS AND SNOW
ACCUMULATIONS UP FOR LATE FRI NIGHT/SAT. WILL TREND QPF TOWARD THE
00Z/12Z ECMWF WHICH ARE VERY SIMILAR AND PROBABLY REPRESENT A GOOD
COMPROMISE BTWN THE DRIER GFS AND THE VERY WET GEM WHICH GENERATES
OVER 0.75 INCHES OF PCPN ACROSS THE SE FCST AREA. 24HR PCPN ENDING
AT 00Z/28 DEC ON THE ECMWF RANGES FROM AROUND 0.15 FAR W TO
0.35-0.45 INCH ACROSS THE SCNTRL AND E. NAM/GFS FCST SOUNDINGS SHOW
FAIRLY VIGOROUS UPWARD MOTION THRU THE DGZ...SO SNOW RATIOS MAY END
UP AROUND 15/1 OR SO...SUGGESTING A GOOD POTENTIAL FOR ADVY LEVEL
SNOW ACCUMULATIONS FOR THE SCNTRL AND E FCST AREA LATE FRI NIGHT/SAT
IF THE HEAVIER QPF UTILIZED IN THIS FCST VERIFIES. THE ARRIVAL OF
DEEP LAYER QVECTOR DIVERGENCE IN THE WAKE OF THE DEPARTING SHORTWAVE
LATER IN THE DAY WILL CAUSE THE SYNOPTIC SCALE SNOW TO DIMINISH W-E.
ARRIVAL OF 850MB TEMPS AS LOW AS -12C TOWARD 00Z SUN IN THE WNW FLOW
IN THE WAKE OF THE DEPARTING SHORTWAVE WILL BRING A RETURN OF LIGHT
LES FOR SAT EVENING.

SAT NIGHT...LARGER SCALE DNVA/DEEP LAYER QVECTOR DIVERGENCE WILL
DOMINATE MOST OF SAT NIGHT...SUGGESTING LIGHT LES. HOWEVER...MEDIUM
RANGE MODELS DO SHOW SOME INCREASE IN MOISTURE DEPTH AND SOME
SHARPENING OF LAKE INDUCED SFC TROF DURING THE NIGHT. THIS SETUP
COULD SUPPORT SOME INCREASE IN LAKE EFFECT OVERNIGHT SAT NIGHT...
ESPECIALLY ALONG LAKE INDUCED TROF AND WHERE THE LOW-LEVEL NW FLOW
IS MOST FAVORABLE. GFS FCST SOUNDINGS INDICATE FAVORABLE UPWARD
MOTION WITHIN A FAIRLY DEEP DGZ AS WELL. IF SO...MIGHT BE ABLE TO
FLUFF UP A FEW INCHES OF SNOW WHERE LES IS MOST PERSISTENT AND WHERE
UPSLOPING IS STRONGEST.

WITH DECREASING MOISTURE DEPTH AND INCREASINGLY ANTICYCLONIC LARGER
SCALE LOW-LEVEL FLOW...LES ON SUN WILL BE LIGHT FOR AREAS FAVORED BY
NW FLOW.

MON/TUE...INCREASINGLY COLDER AIR FLOWS INTO THE UPPER LAKES WITH
850MB TEMPS FALLING TO -20 TO -24C DURING THAT TIME...RESULTING IN
SFC TEMPS FALLING TO BLO NORMAL VALUES FOR LATE DEC. WITH SUCH COLD
AIR...EXPECT NMRS SNOW SHOWERS IN THE SNOW BELTS FAVORED BY NW
WINDS. GFS FCST SOUNDINGS SHOW INVERSIONS BASED BLO 5KFT...SO LES
WILL OVERALL BE ON THE LIGHT SIDE...MOSTLY SUB ADVY. SINCE THE DGZ
WILL DOMINATE THE CONVECTIVE LAYER...MIGHT BE ABLE TO FLUFF UP SOME
ADVY LEVEL ACCUMULATIONS WHERE LOW-LEVEL CONVERGENCE FOCUSES HEAVIER
SNOW SHOWERS. A COUPLE OF WEAK SHORTWAVES ARE FCST TO SWING THRU THE
UPPER LAKES...ONE MON AND THE OTHER TUE. IT LOOKS LIKE THE ONE ON
TUE MAY HAVE SOME IMPACT ON MOISTURE DEPTH/INVERSION HEIGHTS...SO
LES MAY PERK UP FOR A SHORT TIME ON TUE.

LOW-LEVEL WINDS WILL BACK TO THE WSW ON NEW YEARS EVE IN RESPONSE TO
A STRONG SHORTWAVE DIVING SE THRU NRN MANITOBA AND ASSOCIATED DEEP
SFC LOW PRES SETTLING OVER HUDSON BAY. AS A RESULT...LES SHOULD
SHIFT TO AFFECT MAINLY THE KEWEENAW PENINSULA. TIGHTENING PRES
GRADIENT WILL RESULT IN INCREASING SFC WINDS...ESPECIALLY OVER THE
EXPOSED KEWEENAW. BLSN MAY BECOME AN ISSUE THERE ON NEW YEARS EVE.

NEXT ARCTIC COLD FRONT SHOULD THEN SWEEP ACROSS THE AREA ON NEW
YEARS DAY...ENHANCING LES AND PROBABLY BRINGING AT LEAST A LITTLE
-SN TO THE REMAINDER OF THE AREA.
&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1204 AM EST FRI DEC 26 2014

OVERNIGHT...A COUPLE WEAK DISTURBANCES WILL SHIFT NORTHEAST THROUGH
UPPER MICHIGAN. THE FIRST WAVE WILL LARGELY AFFECT CENTRAL UPPER
MICHIGAN AND HAVE SHOWN A PERIOD OF MVFR VISIBILITIES AS THE SNOW
MOVES THROUGH KSAW. AS THE SECOND WAVE ARRIVES OVERNIGHT...THE
BETTER SNOWFALL WILL SHIFT TO THE NORTHWEST AND AFFECT KCMX/KIWD.
EXPECT VISIBILITIES TO LARGELY STAY MVFR...BUT DID BRING KIWD DOWN
TO IFR FOR A PERIOD LATE TONIGHT INTO FRIDAY AS WINDS SHIFT TO THE
NORTH AND LAKE ENHANCEMENT INCREASES THE SNOWFALL INTENSITY.
CONDITIONS WILL STAY MVFR AT KCMX THROUGH THE PERIOD AND WILL GO TO
IFR AT KSAW IN THE EVENING AS UPSLOPE NORTH WINDS BRING IN A LOWER
CIG FROM LAKE SUPERIOR MOISTURE.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 248 PM EST THU DEC 25 2014

SOUTHWESTERLY WINDS HAVE INCREASED OVER LAKE SUPERIOR (UP TO 25KTS)
BETWEEN A DEPARTING HIGH PRESSURE RIDGE AND A TROUGH IN MINNESOTA.
THIS TROUGH WILL WEAKEN AS IT MOVES OVER LAKE SUPERIOR TONIGHT AND
THEN STALLS OVER FAR EASTERN LAKE SUPERIOR FRIDAY INTO FRIDAY
NIGHT. THIS WEAK PRESSURE GRADIENT WILL ALLOW WINDS TO SHIFT TO THE
NORTH AND FALL BELOW 15KTS TONIGHT AND REMAIN INTO FRIDAY NIGHT. A
LOW MOVING NORTHEAST ALONG THE TROUGH ON SATURDAY WILL INCREASE
THE NORTH AND EVENTUALLY NORTHWEST WINDS ON SATURDAY AFTERNOON AND
SATURDAY NIGHT...WITH GUSTS UP TO 30KTS OVER THE EASTERN LAKE. THE
REST OF THE PERIOD WILL EXPERIENCE NORTHWEST TO NORTHERLY WINDS
UNDER 25KTS AS A STRONG HIGH BUILDS INTO THE NORTHERN/CENTRAL
PLAINS.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&

$$

SHORT TERM...SRF
LONG TERM...ROLFSON
AVIATION...07
MARINE...SRF





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